Abstract
Purpose: :
Mitomycin C is frequently used to retard wound healing after glaucoma surgery. High dose Mitomycin C substantially increases toxicity-related complications. There is potential benefit from either replacement of Mitomycin C or adjunctive use of agents that increase its therapeutic activity when used at a low dose. We investigated the effect upon Mitomycin C induced apoptosis of agents inhibiting channel p-glycoprotein activity in primary human tenon fibroblast cell culture.
Methods: :
Fibroblast cell lines were established by explant culture from human tissue biopsy samples obtained during trabeculectomy procedures. Cells were exposed to mitomycin C at varying concentrations (0.01 - 0.4 mg/ml) for 3 minutes, prior to washing in the presence or absence of the following drugs: Staurosporine (0.003mg/ml); Verapamil (2.5 - 0.25mg/ml); or cyclosporine (50 - 0.5mg/ml). All are thought to bind and inhibit activity of P-gp for separate P-gp substrates. Following exposure, cells were cultured for 6 Hrs and surviving cells counted using a haemocytometer.
Results: :
Both verapamil and staurosporine exhibited mild toxic effects on their own but greatly enhanced the apoptotic effect of Mitomycin C. Low doses of verapamil were used to mimic a clinically acceptable dose administered topically. Doses as low as 0.25mg/ml verapamil continued to show significant augmentation of the apoptotic effect of mitomycin C. Cyclosporine 0.5mg/ml (the concentration commercially available in dry eye medication) modestly augmented of the effect of mitomycin C.
Conclusions: :
Verapamil and Cyclosporine in clinically acceptable concentrations potentiate the effect of Mitomycin C and may obviate the need for high dose anti-metabolites in trabeculectomy.
Keywords: wound healing • drug toxicity/drug effects